(a) Technical Field
The present invention relates in general to a solar cell. More particularly, it relates to an organic thin film solar cell manufactured by stacking a transparent electrode layer, a photoactive layer, and a metal electrode layer on a substrate, and a method for manufacturing the same.
(b) Background Art
Recently, as global warming becomes more of an issue, technology for using environmentally-friendly energy has attracted much attention. An attractive field, in particular, is solar cells using new and renewable energy.
Examples of such solar cells include silicon-based solar cells, thin film solar cells using inorganic substances such as copper indium gallium selenide (CIGS, Cu(InGa)Se2), dye-sensitized solar cells, organic solar cells, organic-inorganic hybrid solar cells, and the like.
Among them, the organic thin film solar cells, which are inexpensive and have a wide application range, have attracted attention in the field of clothing as well as in the fields of architecture and electronics.
Like the dye-sensitized solar cells, the organic thin film solar cell has a solar cell system which absorbs visible light and produces electricity by a photoelectric conversion mechanism.
However, the dye-sensitized solar cell has certain disadvantages in that it uses expensive rare metals such as ruthenium and its manufacturing process is complicated. On the other hand, the organic thin film solar cell has certain advantages in that its manufacturing cost is low since it is formed of inexpensive polymeric dye synthesized using organic substances extracted from petroleum and it can be manufactured using roll-to-roll equipment used in a typical film formation process.
Typically, the organic thin film solar cell is manufactured by forming a thin film coating layer by spin coating, spray coating, or roll-to-roll process. Moreover, a nanoscale bulk-heterojunction structure is formed to suitably improve the photoactivity using the above processes. This structure allows electrons and holes generated by photons to be efficiently separated, which increases energy conversion efficiency.
However, the bulk heterojunction structure with a nanopattern may be broken by phase separation, which easily occurs at a high temperature (e.g., above 100° C.) and, as a result, the energy conversion efficiency is considerably reduced, which is a problem in terms of long-term durability. In order to solve these problems, a study on the implementation of a fixed physical pattern has been carried out.
Recently, while research on the fabrication of nanopattern using a semiconductor process has been conducted, it takes a considerable amount of time to fabricate the nanopattern due to a large number of processes and it also requires expensive equipment.
Accordingly, there is a need in the art for a method for manufacturing an organic thin film solar cell by a simpler process.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.